Rupert Murdoch's BSkyB has bought the exclusive rights to the entire HBO TV catalogue, which includes a huge range of American shows such as The Wire, True Blood, The Sopranos and Martin Scorsese's eagerly-awaited crime drama Boardwalk Empire, MediaGuardian can reveal.

The satellite TV company has signed a content deal with HBO, the US channel that revolutionised the television market by launching a pay-TV service that screens big-budget dramas. The Sky deal, expected to be announced this morning, will give Sky access to HBO's archive and all forthcoming shows over the lifetime of the agreement. It is believed to be worth around £150m over five years.

The acquisition forms part of a push by Sky to improve its non-sport content as it tries to increase subscriber numbers. The company currently has 9.7 million customers, but is expected to announce today that it has added another 450,000 new subscribers when it unveils its annual results. It is on track to hit a 10 million target by the end of 2010.

The deal also illustrates the huge financial firepower Sky has at its disposal. It will spend £1.7bn on content this year, the majority of it on sports and film rights. Five, which was bought by Express Newspapers owner Richard Desmond last week, has an annual programming budget of around £165m. BBC2, which screened all five series of The Wire last year, spends around £500m on content each year.

Sky will now be able to screen some of the defining US television shows of the past decade, including The Sopranos and Sex and the City. It also has the rights to several series currently shown by rival broadcasters, including Entourage, which is shown on ITV2, and Curb Your Enthusiasm, which was broadcast on Channel 4. Sky will begin screening those series when the current deals with rival terrestrial channels expire. Other HBO shows that have been cancelled but remain popular include macabre black comedy Six Feet Under.

The first HBO series to be shown on Sky will be Scorsese's gangster drama Boardwalk Empire. Set in the east coast resort town of Atlantic City in the 1920s, it stars Steve Buscemi as a mob boss who makes a fortune importing illegal alcohol. It makes its debut on HBO in America in September and will be shown on Sky shortly after.

Sky One, the broadcaster's entertainment channel, already shows Pacific, Steven Spielberg's 10-part drama set in the second world war. As part of the latest deal, Sky will also hold the rights to Band of Brothers, the Hollywood director's war saga that revolved around the D-Day landings in Normandy.

Sky is investing a huge amount of money in new programming by acquiring hit shows and commissioning original content. It is trying to position Sky Arts as the country's premier cultural channel as it attempts to demonstrate to politicians and regulators that it can produce programming that was once the preserve of public service broadcasters like the BBC.

Despite repeated attempts Sky has so far failed to find a homegrown TV hit, however, and has relied on buying in programmes from abroad.

Sky One launched a general entertainment show, Got to Dance, fronted by Big Brother host Davina McCall last year, but it did not win big audiences. It lured Harry Enfield from the BBC in a big-money deal in 2000, but Harry Enfield's Brand Spanking New Show was a career low point.

Despite repeated attempts to diversify, the business remains reliant on sports content, most notably the Premier League, although it points out that only 5% of viewing is football-related.

Sky's results are expected to show it made a pre-tax profit of around £850m in the 12 months to the end of March 2010, up from £813m in the last financial year.

It is expected to make £1bn in 2011 for the first time. Sky is thriving at a time when commercial rivals, including ITV and Channel 4, are seeing profits fall dramatically. Channel 4 made a pre-tax profit of £300,000 this year after cutting costs.

One in every two of the country's 23m households now has pay-TV and Sky dominates the market. It will make HBO's shows available on its catch-up TV service Sky+, which will relaunch shortly.